Resistive Touch Screen Measurement System

1. A resistive touch screen measurement system comprising: a first switch having a first terminal coupled to a first voltage source; a second switch having one terminal coupled to a second voltage source; a first resistor coupled to the first switch and the second switch in a series connection; a comparator having a first input coupled to a second terminal of the first switch; a successive-approximation register having an input coupled to an output of the comparator; and a simulation circuit comprising: a second resistor; a third switch having a first terminal coupled to the first voltage source, and a second terminal coupled to the second resistor and a second input of the comparator; a fourth switch coupled to the second resistor and the second voltage source; a fifth switch set having a plurality of switches, each switch coupled to the second resistor and the first voltage source in a parallel connection with the third switch, and a control terminal of each switch of the fifth switch set coupled to an output of a set of outputs of the successive-approximation register; a sixth switch set having a plurality of switches, each switch coupled to the second resistor and the second voltage source in a parallel connection with the fourth switch, and a control terminal of each switch of the sixth switch set coupled to an output of the set of outputs of the successive-approximation register; and a set of inverters, each inverter coupled to a control terminal of a switch of the fifth switch set and an output of the outputs of the successive-approximation register.

2. The touch screen measurement system of claim 1 wherein the first switch, the third switch, and all the switches of the fifth switch set are P-type metal oxide semiconductors (PMOS).

3. The touch screen measurement system of claim 1 wherein the second switch, the fourth switch, and all the switches of the sixth switch set are N-type metal oxide semiconductors (NMOS).

4. The touch screen measurement system of claim 1 further comprising a seventh switch coupled to the first input of the comparator and a second terminal of the first switch.

5. The touch screen measurement system of claim 1 further comprising: an eighth switch having a first terminal coupled to the first voltage source; a ninth switch having a terminal coupled to the second voltage source; a third resistor coupled to the eighth switch and the ninth switch in a series connection; and a tenth switch coupled to the first input of the comparator and a second terminal of the eighth switch.

6. The touch screen measurement system of claim 5 wherein the eighth switch is a P-type metal oxide semiconductor.

7. The touch screen measurement system of claim 5 wherein the ninth switch is an N-type metal oxide semiconductor.